Modified locust bean gum, solution thereof, and process for making a locust bean gumsolution



Patented July 7, 1953 UNITED STATES PATENT OFFICE MODIFIED LOCUST BEAN GUIVI, SOLUTION THEREOF, AND PROCESS FOR MAKING A LOCUST BEAN GUM SOLUTION Nat Frisch, White Plains, and Frank J. Sweeney,

Forest Hills, N. Y., assignors to Stein, Hall & Company, Inc., New York, N. Y., a corporation of New York No Drawing. Application December 16, 1948, Serial No. 65,718

Claims. (01. 10e ,2os)

The present invention relates to locust bean gum, modified to render it readily dispersible in water, to a method of dispersing and gelatinizing locust bean gum in water, and to an aqueous solution thereof. a

It has been known for some time that locust bean gum powder or flour, which is obtained from the fleshy seeds in the fruit of the locust or carob tree (Ceratonia siliquc) a perennial legume native to the Mediterranean region, has desirable adhesive and de'fiocculating properties which make it useful in the preparation of felted sheet material such as paper. It has also been known, however, that it is extremely difficult to' disperse locust bean gum uniformly in water so that its ability to defloc culate fibers suspended in an aqueous medium can be used to advantage in the manufacture of paper and other felted sheet material.

Thus, for example, a slow addition of one part by weight of straight locust bean gum powder to 100 parts by weight of water while stirring, and the subsequent heating thereof to a temperature of 190200 IE. will result in an incomplete dispersion and solution of the locust bean gum, as evidenced by the presence of lumps'that must be strained out before use. Furthermore, the containers and other equipment used in the prep aration of an aqueous locust bean gum solution must frequently be cleaned to remove a thick and gummy scum formed on all parts that come in contact with the gum. The great amount of free of lumps and does not require strainingbefore it is used as an additive to an aqueous suspension of fibrous material such as, for example, a stock suspension from which paper is made; It forms no scum, leaves the mixing equipment clean and obviates the necessity of using special equipment such as strainers and injectorsin'its preparation. The mixture need not be added slowly, as is necessary with straight locust bean gum, but can be dumped directly into cold water without increasing its liability to form lumps.

The proportions of the various components may vary widely, depending on the results desired. Generally no difficulty is experienced in dispersing mixtures containing up to about 90%' by weight of locust bean gum powder. As .the proportion of locust bean gum powder increases from 90% and approaches 100% ,"the difiiculty of dispersing the mixture in water increases'by, degrees but mixtures containing as high as 96% locust bean gum powder can, if added gradually and stirred vigorously, be dispersed without forming lumps either before or after cooking.

Itis surprising also that, weight for weight,

the mixture has, within the limits of measurable error, beneficial efiects on the final felted sheet material that are superior to those obtained with patience required to obtain a dispersion of the gum and the extra time and equipment made necessary thereby are apparently responsible for the limited use that has heretofore been made of locust bean gum in spite of its otherwise promising characteristics.

It has now been found that locust bean gum 1 can be readily dispersed in water in the presence of a borate such as, for example, sodium tetra borate (borax) and sodium meta borate, and

an aldehyde selected from the group consisting of glyoxal and pyruv'ic aldehyde. sults are obtained when the borate and the aldehyde are thoroughly admixed, in the dry state, with locust bean gum powder prior to the addition thereof to water.

Itis surprising that a mixture of locust bean gum powder, even with relatively small proportions of borate and aldehyde, is dispersible without difiiculty in cold water.

about 200 F., the locust bean gum "opens or swells to form a clear, viscous solution that is Optimum reproportion of locust bean gum powder should; generally range between about and 96 %',"the

When the dispersion is cooked, e. g., by raising its temperature to straight locust beangumfso long. as the, proportion of locust bean gumin the mixture is not" substantially below'about 50%. Thus, for ex-- ample, it has been found that the bursting, tearing and folding strengths of paper produced by addition tothe suspendedstock at a rate of five pounds of a mixture consisting of locustbean gum,- 10% borate and 5% aldehyde in dis- 1 persed form per ton of paper stock, based on the dry weight, are superior to those produced by the addition of straight; locust bean gum at the same rate. v I In view of the foregoing: considerations, "the The relativeproportions of borate andalde 3 hyde may also vary and depend upon the consistency and characteristics desired in the aqueous solution formed when the mixture is added to water and cooked. Theborate tends to impart to the cooked solution a heavy body, high film strength and stringiness. The aldehyde reduces the ropiness of the cooked solution and imparts a long stringy character thereto. It has generally been found desirable to adjust the relative proportions of locust bean gum, borate and aldehyde so that the solution or dispersion thereof in water will have a pH between-3and 10 and preferably at about 8.0 to 8.2. The ratio ofrborate to aldehyde may vary fromaabout 1:1 to 3:1 and is preferably about 2:1. The proportions by weight in the mixture are desirably from about 2% to about 35%, preferably from about to about of borate and from about 1% to about preferably from about 2% to about 6%,.aldehyde.

taining 99% by weight of water, to add the mixture to half the required amount of water at tap or room temperature, stir and heat it to about 200 F. and then add the remainder of the water.

The solution formed by thismethod is transparent, viscous and stringy at room temperature and is sufiiciently free flowing at temperatures of the order of 160 to 185 F. to be pumped without I difiiculty'through 1" pipes.

It is 'to'be understood that other materials,

compatible with the three essential ingredients,

may be added. Thus; for example, starch may be added if it is desired to reduce the proportion of locust bean gum below about 80%. Small amounts of oxidizing agents, such as barium peroxide and'sodium perborate may be added to thin out the solution prepared when the combination is dissolved in Water.

The mixture may be formed simply by thoroughly mixing the components together in the dry state. Where glyoxal, which is normally in the liquid state, forms one of the components, it is sprayed on one or more of the other components prior to or during the dry mixing operation.

'Without intending to limit in any way the scope of the present invention, a number of typical formulae are listed in Tables ,1 and 2 below; the numerals'therein' referring to percent- To further illustrate the utility of the mixture of this invention and of the aqueous solution thereof, and to compare'its eilicacy in the production of paper, the following examples are ineluded. p

7 v Example 1 .Four batches of locust bean gum, borax and glyoxal, corresponding to Formulae Nos. 1, 2, 3 and 4 of Table 1, were made up on a laboratory scale. A 1% aqueous solution of each batch was formed by dispersing one part by weight ofthe drytmixture in about'50 partsby weightiof water, cooking the resulting dispersion to 200 ;F.--an d then adding sufiicient additional water to bring the concentration of solids down to 1 by Weight; The temperature of these solutions was maintained at about 180 F.

. A 1% solution of locust bean gum alone-was prepared in a similar manner.

A number ofpaper making runs, on a laboratory scale, corresponding to the number of solutions prepared, were then made. In each run,-one of the prepared solutions wasadded to the furnish at a rate of 10 lbs., based on the dry weight, of solution to a ton of furnish, likewise based on the dry weight. f

.Two sheets each havingsa weight of 2.8 grams were selected from each .run to eliminatvtest errors due to variations in the Weight of :the

ages by weight. sheets produced and each sheet selected was TABLE .1

Formula N04; 1 2 a 4 5 e 7 s 9 1o 11 Locust Bean Gum s5 s7 90 90' T85 85 80 70 e0 '50 .84

Borax. 10 '7 .5 6 10 10 12 20 126.6 33.3 ,11

Pyruvic Aldehyde 5 2 Ammonium Chloride 5 3 5 8.4 11.7 3

TABLE 2 Formula No 12 13' 14 15 16 17 1s 19 -2o 21 Locust Bean Gum "I 85 84 85 Powdered Potato 'Starch orax Sodium Metaborate Glyoxal l. Citric Acid l Boric Acid Aluminum Sulfat BariumPeroxide" Sodium Perborate D'owicide A subjected to ten mu'l-len tests. The averages of the twenty mullen tests in each runare tabulated below:

Average 7 Mullen Formula No.

7 ou t Locust Bean Gum Alone I Example 2 Dry mixtures correspondingto Formulae Nos. '7, 8, 9,' 10, 11, 13, 14, 16; -13, 19 and" 20 were made up, on a laboratory scale; into 1% aqueous solutions by dispersing 'one-part'by; weight of each dry mixture in about 50 parts by weight in water, cooking the resulting dispersions to 200 F: and then adding sufiicient additional water to bring the concentration of solids down to 1% .by weight.

The temperature of these solutions was main-.

tained at about 180 F. A number of paper making runs on a laboratory scale were then made. In each run, a number of blank and modified paper sheets were made. The blank sheets were made without adding a locust bean gum containing solution to the furnish and the modified sheets were made by adding one of the prepared solu tions at a rate of 10 lbs., based on the dry weight, of solution to a ton of furnish, likewise based on the dry weight.

Two blank sheets and two modified sheets each having a weight of 2.8 grams were selected from each run to eliminate test errors due to variations in the weight of the sheets produced and each sheet selected was subjected to ten mullen tests. The averages of the twenty mullen tests conducted on each set of two sheets are tabulated below:

Blank Modified Fwmula Sheets Sheets 40. 65 46. 40. 65 44. 9 37. 45. 4 s7. 5 44. 5 42. 1 45. 9 4s. 5 45. 7 44. 5 47. 7 41. e 45. 4 48. 9 52. 4 43. 1 45. 2 42. 7 4s. 5

Example 3 Dry mixtures corresponding to Formulae Nos. 12 and 21 were made up, on a laboratory scale into 1% aqueous solutions by dispersing one part by Weight of each dry mixture in about 50 parts by weight in water, cooking the resulting dispersions to 200 F. and then adding suificient additional water to bring the concentration of solids down to A; to per cent by weight.

A number of paper making runs on a laboratory scale were then made. In each run, a number of blank and modified paper sheets were made. The

blank sheets were made without adding a locust bean gum containing solution to the furnish and the modified sheets were made by adding one of the cooked solutions, at a temperature of approximately 100 F. and at a rate of 10 lbs., based on the dry weight, of solution to a ton of furnish, likewise based on the dry weight.

Two blank sheets and two modified sheets each having a weightof 2.9? plus or minus .03 grams were selected from each run to eliminate test errors due to variations in the weight of the sheets produced and each sheet selected was subjected to ten mullen tests. The averages of the twenty mullen tests conducted on each set of two sheets are tabulated below:

Blank Modified Formula N0 Sheets Sheets Itis to be understood that 'innunierable modtfications will readily occur to'those's'killedjin;the art upon reading'this description;- All such 'mod ifications are intended tobe included withinth'escope of the present inventionas defined in the appended claims:

Weclaimr" 1. A- mixture comprising from about 50% to about 96% by weight of locustbean gum, from about 2% to about by'weight of a sodium borate and from about 1% to about 20% by weight of an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde, the relative proportions of borate to aldehyde ranging from about 1 to 1 to 3 to 1.

2. A. mixture comprising from about 85% to about 90% by weight of locust bean gum, from about 5% to about 10% by weight of a sodium borate and from about 2% to about 6% by weight of an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde, the relative proportions of borate to aldehyde being about 2 to 1.

3. An aqueous solution wherein about 50% to 96% by weight of the solute is locust bean gum, about 2% to 35% by weight of the solute is a sodium borate and about 1% to 20% by weight of the solute is an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde.

4. An aqueous solution wherein about85% to I 90% by weight of the solute is locust bean gum,

about 5% to 10% by weight of the solute is a sodium borate and about 2% to 6% by weight 01' the solute is an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde.

5. A method of preparing an aqueous solution of locust bean gum in water which comprises adding to water a mixture of locust bean gum, a sodium borate and an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde and heating it to a temperature of about 200 F.

6. A method of preparing an aqueous solution of locust bean gum in water which comprises adding to water a mixture containing 50 to 96 parts by weight of locust bean gum, 2 to 35 parts by weight of a sodium borate and 1 to 20 parts by weight of an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde, and heating it to a temperature of about 200 F.

7. A method of preparing an aqueous solution adding to water a mixture containing to partsby weight of locust'bean gum, 5 to 10 parts by weight of a sodium borate and 2 to 6 parts by weight of an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde, and heating it to a temperature of about 200 F.

8. A method of preparing an aqueous solution of locust bean gum which comprises dispersing locust bean gum in water in the presen-ce'of a sodium borate and an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde and heating the dispersion to a temperature of about 200 F.

9. A method of preparing an aqueous solution of locust bean gum which comprises dispersing 50 to 96 parts by weight of locust bean gum in water in the presence of 2 to 35 parts by weight of a sodium borate and 1 to 20 parts byweight of an aldehyde selected from the group consisting of glyoxal and pyruvic aldehyde and heating the dispersion to a, temperature of about 200'F.

10. A method of preparing an aqueous solution of a locust bean gum which comprises dispersing 85 to 90 parts by weight of locust bean gum in water in'the presence of; 5 11010; parts by weight of a. sodium borateandfli tozfi parts by weight of NAT FRISCH.

FRANK J. SWEENEY.

' .Refefences Cited; in the-file of this parent.

8? UNITED STATESPATENTS Number 10 Tagliani: Jour. Soc. Dyers & Cdloufis't, 45,

Name 7 Date Pinel Aug; 4,:1914 Satow Oct. 8, 1918 Braun Jan. 17, 1939 Soholz Sept. 30,1941

Engler .'.W Sept. 17, 1946 OTHER REFERENCES 347 and 8 (1929)]TP890S6. 

3. AN AQUEOUS SOLUTION WHEREIN ABOUT 50% TO 96% BY WEIGHT OF THE SOLUTE IS LOCUST BEAN GUM, ABOUT 2% TO 35% BY WEIGHT OF THE SOLUTE IS A SODIUM BORATE AND ABOUT 1% TO 20% BY WEIGHT OF THE SOLUTE IS AN ALDEHYDE SELECTED FROM THE GROUP CONSISTING OF GLYOXAL AND PYRUVIC ALDEHYDE. 